Date:   Tue, 26 Feb 2019 11:44:13 +0100
From:   Joerg Roedel <joro@8bytes.org>
To:     Stanislaw Gruszka <sgruszka@redhat.com>
Cc:     Lorenzo Bianconi <lorenzo.bianconi@redhat.com>,
        Rosen Penev <rosenp@gmail.com>,
        linux-wireless <linux-wireless@vger.kernel.org>,
        Samuel Sieb <samuel@sieb.net>,
        Alexander Duyck <alexander.h.duyck@linux.intel.com>,
        iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org
Subject: Re: MT76x2U crashes XHCI driver on AMD Ryzen system
Message-ID: <20190226104413.GH20740@8bytes.org>
References: <CAJ0CqmUgPWNJtCW4Q__sOtB8w-YtwW+uZy7crxMNrmSgQ6OFyA@mail.gmail.com>
 <1547404075.1582.0@smtp.gmail.com>
 <CAJ0CqmU7k5i26g7dGPxNdts7Gm67W6qNsr4vYuW05ugsEF1ohw@mail.gmail.com>
 <CAKxU2N-+CTaRdJMFVRdozJ5TTpN+_4thiDRBJBFq8gGtuRVYvA@mail.gmail.com>
 <20190114091841.GA23045@localhost.localdomain>
 <CAKxU2N8ioMszBCyQcH7CVhgBdW4aj7yZ+kYQe14DCV5OSAnxrg@mail.gmail.com>
 <20190115090400.GA2267@localhost.localdomain>
 <20190218143742.GA11872@redhat.com>
 <20190226100535.GA20740@8bytes.org>
 <20190226103450.GA2989@redhat.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20190226103450.GA2989@redhat.com>
User-Agent: Mutt/1.10.1 (2018-07-13)
Sender: linux-wireless-owner@vger.kernel.org
Precedence: bulk

On Tue, Feb 26, 2019 at 11:34:51AM +0100, Stanislaw Gruszka wrote:
> On Tue, Feb 26, 2019 at 11:05:36AM +0100, Joerg Roedel wrote:
> If sg->offset > PAGE_SIZE is fine then most likely we have problem with
> alignment.

The map_sg implementation in the AMD IOMMU driver uses sg_phys() which
handles the sg->page + sg->offset calculation fine.

> Note hat issue is with dma_map_sg(), switching to dma_map_single()
> by using urb->transfer_buffer instead of urb->sg make things work
> on AMD IOMMU.

On the other hand this points to a bug in the driver, I'll look further
if I can spot something there.

Regards,

	Joerg